1. Field of the Invention
The present invention relates to a process for the manufacture of 1,1,1,3,3-pentachloropropane.
2. Description of the Related Art
The Montreal Protocol of 1987 placed a ban on certain substances that deplete the ozone layer, especially chlorofluorocarbons (CFC's). To hasten the elimination of CFC production and use, the Protocol allowed for certain fluorocarbon products (HCFC's) to be used as "bridge replacements." Although these bridge replacements are considerably more ozone friendly than CFC'S, they are intended to be transitional and not permanent replacements. Fluorocarbon producers are actively pursuing replacement HFC candidates known as "third generation fluorocarbons." These third generation fluorocarbons will require hydrochlorocarbon feedstocks.
The second largest U.S. fluorochemical end-use market, next to refrigeration, is for blowing agents utilized in the manufacture various synthetic plastic formed products. CFC-11 was the dominant product in this market, however, it has been replaced by the bridge-fluorocarbon HCFC-141b. Because, by regulation, foam manufacturers must switch away from HCFC-141b by the year 2003, new third generation fluorocarbon products must be developed and commercialized.
Several fluorochemical producers have targeted fluorocarbon 1,1,1,3,3-pentafluoropropane, utilizing 1,1,1,3,3-pentachloropropane as the hydrochlorocarbon feedstock, as the primary replacement product for foam blowing applications. Zil'bennan et al. ("Synthesis of liquid telomers of vinyl chloride with carbon tetrachloride", J. Org. Chem. USSR (English Transl.), 3:2101-2105, 1967) prepared 1,1,1,3,3-penta-chloropropane in a 58% yield by the reaction of carbon tetrachloride (CCl.sub.4) and vinyl chloride using ferrous chloride tetrahydrate in isopropanol. In addition, Kotora et.al. ("Addition of tetrachloromethane to halogenated ethenes catalyzed by transition metal complexes", J. Mol. Catal., 77(1):51-60, 1992) prepared 1,1,1,3,3-pentachloropropane in high yields using either cuprous chloride/butylamine or tris(triphenylphosphine) dichlororuthenium.
European Patent Application No. 131561 describes a very general process for the addition of a haloalkane compound to an alkene or alkyne compound in the presence of iron metal and a phosphorus (V) compound, to form halogenated alkanes. EP 131561 sets forth several examples of the batch reaction of ethylene and carbon tetrachloride to produce 1,1,1,3-tetrachloropropane. EP 131561 also mentions a wide variety of other olefins and alkynes, including vinyl halides. It states that the batch process could be made continuous, but does not include any specifics on how this would be carried out.
Despite the known processes, improvements are needed in the manufacture of 1,1,1,3,3 -pentachloropropane. The present invention is directed to such an improved process.